rbd: add maxsnapshotsonimage flag

Added maxsnapshotsonimage flag to flatten
the older rbd images on the chain to avoid
issue in krbd.The limit is in krbd since it
only allocate 1 4KiB page to handle all the
snapshot ids for an image.

The max limit is 510 as per
https://github.com/torvalds/linux/blob/
aaa2faab4ed8e5fe0111e04d6e168c028fe2987f/drivers/block/rbd.c#L98
in cephcsi we arekeeping the default to 450 to reserve 10%
to avoid issues.
Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

charts/ceph-csi-rbd/templates/provisioner-deployment.yaml

@@ -116,6 +116,7 @@ spec:
             - "--drivername=$(DRIVER_NAME)"
             - "--rbdhardmaxclonedepth={{ .Values.provisioner.hardMaxCloneDepth }}"
             - "--rbdsoftmaxclonedepth={{ .Values.provisioner.softMaxCloneDepth }}"
+            - "--maxsnapshotsonimage={{ .Values.provisioner.maxSnapshotsOnImage }}"
             {{- if .Values.provisioner.skipForceFlatten }}
             - "--skipforceflatten={{ .Values.provisioner.skipForceFlatten }}"
             {{- end }}

charts/ceph-csi-rbd/values.yaml

@@ -113,6 +113,8 @@ provisioner:
   # Soft limit for maximum number of nested volume clones that are taken before
   # a flatten occurs
   softMaxCloneDepth: 4
+  # Maximum number of snapshots allowed on rbd image without flattening
+  maxSnapshotsOnImage: 450
   # skip image flattening if kernel support mapping of rbd images
   # which has the deep-flatten feature
   # skipForceFlatten: false